Having done a lot of riding over a 60lb weight range I feel very qualified to speak to this.
Yes, a 20 lb gain can make quite a big difference in how your seat and leg connects to your horse. Iāve spoken with trainers who have also noticed that itās harder to get your leg on as the thigh gets bigger and thereās more flesh between the bone and the saddle. It definitely can also impact your balance and how quickly you can make small changes to your balance because youāre simply shifting more mass.
Now, let me also say that my experience has been that fittness is MUCH more important than weight, at least within a range that is comfortable for the horse to carry. For a time at the beginning of COVID I gained weight but I also got more sedentary than Iād ever been before. I was working 60 hrs a week tied to a laptop and we were all treating the situation like it was temporaryā¦ And the lack of muscle when I went back to the barn was crazy! I could definitely feel it riding, but I could also tell when I tried to dump a wheelbarrow or move a bale of hay. I was just so weak!
I got the strength back before the weight came off and that was a huge relief. Getting the weight off also helps, but not as much as the strength. So that is where I would recommend any rider focus their attention first. Build a fence, dig a ditch, move hay. Thatās the workout that got me strong again. You want farm muscles, not beach muscles.